<!DOCTYPE html>
<html lang="zh-CN">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
</head>
<body>
   <script src="../dev/vendors/vue.js"></script>
   <div id="example">
    <p>Original message: "{{ message }}"</p>
    <p>Computed reversed message: "{{ reversedMessage() }}"</p>
   </div>
   <script>
    var vm1 = new Vue({
      el: '#example',
      data: {
        message: 'Hello'
      },
      // computed: {
      //   // a computed getter
      //   reversedMessage: function () {
      //     // `this` points to the vm instance
      //     return this.message.split('').reverse().join('')
      //   }
      // }
      methods: {
        reversedMessage: function () {
          return this.message.split('').reverse().join('')
        }
      }
    })
   </script>

   <div id="demo">{{ fullName }}</div>
   <script>
      // var vm2 = new Vue({
      //   el: '#demo',
      //   data: {
      //     firstName: 'Foo',
      //     lastName: 'Bar',
      //     fullName: 'Foo Bar'
      //   },
      //   watch: {
      //     firstName: function (val) {
      //       this.fullName = val + ' ' + this.lastName
      //     },
      //     lastName: function (val) {
      //       this.fullName = this.firstName + ' ' + val
      //     }
      //   }
      // })
      var vm2 = new Vue({
        el: '#demo',
        data: {
          firstName: 'Foo',
          lastName: 'Bar'
        },
        computed: {
         fullName: {
            // getter
            get: function () {
              return this.firstName + ' ' + this.lastName
            },
            // setter
            set: function (newValue) {
              var names = newValue.split(' ')
              this.firstName = names[0]
              this.lastName = names[names.length - 1]
            }
          }
        }
      })
   </script>

   <div id="watch-example">
      <p>
        Ask a yes/no question:
        <input v-model="question">
      </p>
      <p>{{ answer }}</p>
   </div>
   <!-- Since there is already a rich ecosystem of ajax libraries    -->
    <!-- and collections of general-purpose utility methods, Vue core -->
    <!-- is able to remain small by not reinventing them. This also   -->
    <!-- gives you the freedom to just use what you're familiar with. -->
    <script src="https://unpkg.com/axios@0.12.0/dist/axios.min.js"></script>
    <script src="https://unpkg.com/lodash@4.13.1/lodash.min.js"></script>
    <script>
    var watchExampleVM = new Vue({
      el: '#watch-example',
      data: {
        question: '',
        answer: 'I cannot give you an answer until you ask a question!'
      },
      watch: {
        // 如果 question 发生改变，这个函数就会运行
        question: function (newQuestion) {
          this.answer = 'Waiting for you to stop typing...'
          this.getAnswer()
        }
      },
      methods: {
        // _.debounce 是一个通过 lodash 限制操作频率的函数。
        // 在这个例子中，我们希望限制访问yesno.wtf/api的频率
        // ajax请求直到用户输入完毕才会发出
        // 学习更多关于 _.debounce function (and its cousin
        // _.throttle), 参考: https://lodash.com/docs#debounce
        getAnswer: _.debounce(
          function () {
            var vm = this
            if (this.question.indexOf('?') === -1) {
              vm.answer = 'Questions usually contain a question mark. ;-)'
              return
            }
            vm.answer = 'Thinking...'
            axios.get('https://yesno.wtf/api')
              .then(function (response) {
                vm.answer = _.capitalize(response.data.answer)
              })
              .catch(function (error) {
                vm.answer = 'Error! Could not reach the API. ' + error
              })
          },
          // 这是我们为用户停止输入等待的毫秒数
          500
        )
      }
    })
    </script>
</body>
</html>